#include <string>

using namespace std;

class Solution {
public:
    string reverseString(string s) {
        string ret = s;
        
        for (int i = 0, j = ret.size() - 1; i < j; ++i, --j) {
            char s = ret[i];
            ret[i] = ret[j];
            ret[j] = s;
        }
        
        return ret;
    }
};